Seashore paspalum plant ‘Sea Isle 1’

ABSTRACT

A vegetatively reproduced seashore paspalum cultivar, developed from a segregating seed collection of unknown parentage, is named ‘Sea Isle 1’. It is distinguished by high tolerance to salinity, dark green color, fine textured leaves, and high turf quality and density. These distinguishing characteristics make it particularly suitable as a turfgrass for lawns and golf courses.

SUMMARY OF THE INVENTION

The present invention comprises a new and distinct plant of Paspalumvaginatum O. Swartz which has been given the name ‘Sea Isle 1’. Thefollowing traits have been repeatedly observed and are the mostpronounced characteristics of this new cultivar when grown in Georgia,and in combination, they distinguish it from Adalayd®, the most closelyrelated variety.

1. High tolerance to salinity

2. Dark green color

3. Fine textured leaves with high turf quality and density

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the Sea Isle 1 plant growing in a turf setting, producinginflorescences (commonly referred to as spikes), which are highlightedagainst white paper on a clipboard.

FIG. 2 shows typical rhizomes of Sea Isle 1.

DETAILED DESCRIPTION Background of the Invention

Paspalum vaginatum O. Swartz is a grass in the Panicoideae subfamilywhich inherently colonizes saline ecosystems, e.g. along sea coasts andon brackish sands. Commonly referred to as “seashore paspalum”, it is anecologically aggressive, littoral warm-season perennial grass. species.It is both rhizomatous and stoloniferous. Because it can toleratewaterlogged conditions and periodic, meso-saline flooding, it has beenuseful for erosion control on salinity-sensitive lands and areassubjected to tidal influences, e.g. for beach preservation. The grassoccurs in the wild in both hemispheres. In the Americas, it is foundnaturally almost exclusively along the Atlantic coastline in marshy,brackish ecosystems. In Australia, it is found in tropical heaths,tropical and subtropical rainforests, semi-arid shrub woodlands, acaciashrublands, and mangrove swamps.

Generally, P. vaginatum is a self-incompatible, diploid species. Thediploid chromosome number recognized for the species is 20, and thegenome of this species is the “D” genome. It has a C₄ method of carbonfixation, using the NADP-ME pathway, which if characteristic for grassesthat occur in moist ecosystems.

P. vaginatum has been introduced into salt-affected areas as the needfor forages, land reclamation and turf have increased. The varietyAdalayd® has been widely used in Australia as a lawngrass, although itsuse on bowling greens was curtailed when superdwarf bermuda grasses wereintroduced to the country. P. vaginatum was identified on a marsh golfcourse at the Sea Island Golf Club of Georgia, in the southeasternUnited States, where the grass was already established along the golfcourse fairwways when the course was built in 1925. P. vaginatum wasintroduced sporadically throughout the 1970s and 1980s for golf courseand home lawn use, and one variety from Australia became reasonablywell-known in the United States, Adalayd® (U.S. Plant Pat. No. 3,939).However, this variety was not managed effectively in the United States,and the lack of optimization of fertilization regimes and irrigationrequirements led to disenchantment about its performance. With theintroduction of the dwarf bermudagrasses and other warm season grasses,the use of a seashore paspalum variety as a turfgrass has been minimal.In the late 1980s a variety of seashore paspalum was introduced to agolf course in Honolulu, Hi., from Sea Island, Ga., and is now referredto as ‘Salam’ (an unpatented variety).

With increasing pressures on golf course developers to use coastalvenues and reclaimed water sources (or brackish water), there is a needfor a high-quality seashore paspalum turfgrass adapted to the UnitedStates.

ORIGIN OF THE INVENTION

Sea Isle 1 is a selection from a segregating seed collection of unknownparentage from Argentina. Sea Isle 1 was selected on the basis of itsaggressive growth habit and tolerance to close mowing, importantattributes for turf user.

PROPAGATION

Sea Isle 1 can be propagated asexually through sprigs or sod. Spriggingrates can vary from a minimum of 5 bushels per 1000 ft² (200bushels/acre) to normal warm-season grass rates of 400-6000 bushels peracre. To establish purity and minimize cross-contamination in plots,single stolons of Sea Isle 1 were initially planted in soilless media,then continuously increased in the greenhouse until ready for fieldplanting on golf courses or sports fields. Foundation fields are plantedfrom this greenhouse-grown material. Asexual reproduction demonstratesthat the unique features of ‘Sea Isle 1’ are stable and are reproducedtrue-to-type in subsequent generations. Sea Isle 1 was asexuallypropagated at the Georgia Agricultural Experiment Station, College ofAgricultural and Environmental Sciences, Department of Soil and CropSciences, Griffin, Ga., U.S.A.

Sea Isle 1 can also be propagated through in vitro tissue culturing (forgeneral protocols, see C.A. Cardono and R.R. Duncan 1997 Crop Science37:1297-1302). The best explants for induction of embryogenic callus areimmature inflorescences.

Botanical description:

Culms.—The flowering culms are erect or basally decumbent, ranging inheight from 8-15 cm (unmowed) with 5-8 glabrous nodes.

Leaves.—Mid-culm leaves are fine-textured, do not have sheath or bladeauricles, and are distichous. The blades are 50 mm long, approximately 2mm wide, linear and glabrous, tapering to a narrow apex. The prophyllumis 20 mm long. The 1 mm ligule is membraneous and truncate with apubescent collar. The leaf edges are smooth and the leaf veins areobscure.

Stolons.—Nodes are pubescent, and the internode length is 7-9 mm.

Inflorescence.—The inflorescence is composed of two primary racemes,20-25 mm in length, with 16-25 twin-rowed spikelets on each primaryraceme, and is fully exserted at maturity. Each spikelet is solitary,plano-convex, subsessile, elliptic, 2.5 mm long, and 0.9-1.5 mm wide.Anthers are 1.2-1.4 mm long. The glumes are glaborous.

Seed.—Rarely produced, but are typically 2.5 mm long and 1.5 mm wide,narrowly obovate, subacute, and slightly concavo-convex. The seed isstraw-colored when mature.

Salt tolerance and growth rates.—Sea Isle 1 was compared to the varietyAdalayd® in a standard laboratory salinity stress study. As shown inTable 1, Sea Isle 1 was consistently more tolerant of salt, both interms of its growth at a relatively high salt concentration (40deciSiemens per meter, or dSm⁻1) as well as in the amount of salinityrequired (EC) to result in a 25% reduction in growth (for comparison,ocean water has a conductivity of 54 dSm⁻1). In addition, Sea Isle 1 ismore aggressive in its overall growth rate in the absence of salt.

TABLE 1 EC @ Growth (g/container^(a)) growth reduction No Salt 40 dSm⁻dSm⁻ Shoot Root Shoot Root Shoot Root Adalayd ® 0.23 0.20 0.08 0.13 7.6415.79 SEA ISLE 1  0.70*  0.42*  0.22*  0.32* 16.58 16.98 F test *** ****** *** 0.38 0.38 Crown Total Crown Total Adalayd ® 0.57 1.00 0.37 0.59SEA ISLE 1 0.80  1.92* 0.63^(#)  1.17* F test *** *** *** *** ***, **,*, ^(#) 0.001, 0.01, 0.05, and 0.1 probability levels, respectively(Dunnett T Test; Steele and Torrie, 1960, Principles and Procedures ofStatistics, McGraw-Hill, New York) ^(a)5 cm top diameter × 20 cm depth =container

Leaf color.—The color of turfgrasses can vary significantly depending onenvironmental conditions. When compared side-by-side, the followingRoyal Horticultural Society color chart values are obtained for Sea Isle1 and Adalayd®: Sea Isle 1: 137B. Adalayd®: 138A.

Turf quality.—Sea Isle 1 is a fine-textured cultivar (smaller leaves andshorter internodes) when compared to Adalayd®, which is anintermediate-textured cultivar. When mowed at the same height, Sea Isle1 has a more dense canopy than Adalayd®. Overall turf quality ratings,on a scale of 1.0 to 9.0, where 9.0 is the best, are 8.0 for Sea Isle 1and 5.0 for Adalayd®. The overall turf quality rating is a visual ratingbased on cosmetic appearance, color, leaf texture, denseness of canopyand uniformity of stand.

Disease resistance.—Sea Isle 1 has good resistance to dollar spot, andmoderate laboratory resistance to mole crickets. Field mole cricketevaluations reveal that there is no significant loss in turf shootquality with heavy infestations.

